Field effect transistors comprising a plurality of interdigitated source and drain fingers above an electrically conducting channel are known. The fingers are spaced apart to define gate channels. A gate is arranged in each gate channel. The operation of such field effect transistors is known and will not be described in detail.
A problem with such a known field effect transistor is lack of uniformity in gate dimensions across the FET. Due to the manufacturing process gates towards the edge of the FET tend to be slightly wider than the gates towards the centre. This results in inferior performance of the FET. A wider gate results in lower operating speed. In the case of a FET comprising gates of different widths the speed is limited by the slowest part. Optimum speed is achieved when all the gates have the same small dimensions. The present invention seeks to overcome this problem.